The present invention relates to ink-jet heads.
In the art, there are known ink-jet heads capable of recording by making utilization of the piezoelectric effect of piezoelectric elements. For example, such a type of ink-jet head is disclosed in Japanese Unexamined Patent Gazette No. H05-18735. This ink-jet head includes a head main body, wherein an actuator having a piezoelectric element is utilized to cause droplets of ink to be emitted through an ink nozzle.
A head main body of a typical ink-jet head contains therein a plurality of pressure chambers, to each of which there is fed a supply of ink, and a common ink chamber in communication with the pressure chambers. Formed in a face on the front side of the head main body, i.e., a front face of the head main body, are a plurality of ink nozzles which correspond to the pressure chambers, respectively. On the other hand, provided in a face on the back side of the head main body, i.e., a back face of the head main body, are oscillating plates, each of which constitutes a portion of a compartment wall of each pressure chamber. A common electrode, a piezoelectric element, and an individual electrode are laminated together in sequence on a back side of each oscillating plate. These components (i.e., the oscillating plate, the common electrode, the piezoelectric element, and the individual electrode) together constitute an actuator by which pressure is applied to the pressure chamber, thereby to produce drive force for the emission of droplets of ink through the ink nozzle.
In order to drive the actuator, it is necessary to provide, in addition to the head main body, a driver IC for outputting a drive signal to the actuator. If the driver IC is provided in a printer main body, this results in the requirement that a corresponding number of drive signal lines to the number of ink nozzles are to be extended, by means of FPC or the like, from the printer main body towards the head main body.
In order to achieve a shortening of the drive signal line length, the driver IC is mounted near a lateral face of the head main body (i.e., a face of the head main body perpendicular to a face where ink nozzles are arrayed), in a latest type of ink-jet printer, wherein, from the driver IC disposed in the vicinity of the head main body, a corresponding number of drive signal lines to the number of ink nozzles are extended, by means of FPC or the like, to the head main body. Additionally, the H05-318735""s ink-jet head intends to reduce manufacturing costs by cutting the provision of signal lines between the printer main body and the ink-jet head to such an extent that there are provided only signal lines for the driving of IC. To this end, a driver IC 121 is mounted on an oscillating plate 103 of a head main body 100, as shown in FIG. 13. More specifically, the driver IC 121 is mounted side by side with piezoelectric elements 102 and a common electrode 104. FIG. 13 further shows pattern wires 122 for establishing connections between the driver IC 121 and the individual electrodes.
In the foregoing patent gazette, however, the driver IC 121 is mounted directly onto the oscillating plate 103, which results in the requirement that the driver IC 121 is mounted at a distance away from an actuator 101 for avoiding an actually oscillating portion of the oscillating plate 103 (i.e., an area of the oscillating plate 103 where the piezoelectric elements 102 are positioned). Conversely, it is necessary to secure an extra space for the mounting of the driver IC 121 on the back face of the head main body 100. This increases the surface area of the head main body 100, therefore resulting in increasing the overall size of the ink-jet head. Further, even when a certain structure is employed in which the driver IC is positioned in the vicinity of a lateral face of the head main body, it is still necessary to secure a space for the mounting of the driver IC beside the head main body, therefore making it difficult to reduce the overall size of the ink-jet head.
Bearing in mind the above-described problems with the prior art techniques, the present invention was made. Accordingly, a major objet of the invention is to achieve a downsizing of the ink-jet head.
The present invention achieves the object by employing an arrangement in which a driver IC having a drive circuit is placed on a side, as opposed to the ink emitting direction side where ink nozzles are arranged.
The present invention embodies an ink-jet head. This ink-jet head comprises:
(a) a head main body in which a plurality of nozzles, a plurality of pressure chambers which correspond to the plurality of nozzles, respectively, and a plurality of actuators which correspond to the plurality of nozzles, respectively, are provided,
(b) a driver IC in which a drive circuit for outputting a drive signal to each of the plurality of actuators is provided,
(c) connecting members for establishing connection between the drive circuit and each of the plurality of actuators so that the drive signal is transmittable therebetween,
wherein the plurality of nozzles are arrayed on a first side of the head main body, and
wherein the driver IC is mounted on an opposite second side of the head main body.
Since the driver IC is provided on a side of the head main body opposite to the side where the nozzles are arrayed, this eliminates the need for the provision of a space for the placement of the driver IC beside the nozzle array, thereby reducing the overall size of the ink-jet head. Further, with the downsizing of the ink-jet head, it becomes possible to reduce head manufacture costs.
It is preferred that the plurality of actuators are arranged on the second side of the head main body on which the driver IC is mounted.
It is arranged such that the distance between the driver IC and actuator is made shorter, thereby shortening the connecting members used to establish connection between the drive circuit and each actuator.
An arrangement may be made, wherein each of the plurality of actuators includes an input terminal coupled to a corresponding one of the connecting members and a drive portion for producing drive force used to emit ink through a corresponding one of the plurality of nozzles upon receipt of the drive signal, wherein a drive portion group composed of an array of the drive portions of the plurality of actuators is provided on the second side of the head main body on which the driver IC is mounted, and wherein the driver IC is mounted so as to lie astride the drive portion group.
Since the driver IC is mounted so as to lie astride the actuator drive portion group, this secures space used for the operation of the actuator drive portions. As a result, the operation will be carried out smoothly.
An arrangement may be made, wherein the driver IC is, at both ends thereof, fixedly supported on the head main body, and wherein the connecting members are bonding wires for establishing connection between the input terminals of the plurality of actuators and corresponding output terminals of the drive circuit.
It is arranged such that the driver IC is, at the both ends thereof, supported on the head main body. This facilitates the realization of a structure which enables the driver IC to lie astride the actuator drive portion group. Additionally, it is a bonding wire which establishes connection between the input terminal and the output terminal. Accordingly, it is easy to provide connection between the input and output terminals.
An arrangement may be made, wherein the input terminals of the plurality of actuators are arrayed along a first direction in parallel with the driver IC, and wherein a length of the driver IC in a second direction normal to the first direction is set shorter than a length of the actuator drive portion group in the second direction.
As a result of such arrangement, there is created, along the second direction, a clearance between an output terminal of the drive circuit of the driver IC and an input terminal of the actuator of the head main body. This facilitates connecting together the output terminal of the drive circuit of the driver IC and the input terminal of the actuator of the head main body. In addition, wire bonding processes become easy to perform and the state of input terminal to output terminal connection is improved.
An arrangement may be made, wherein the connecting members are bumps for establishing connection between the input terminals of the plurality of actuators and corresponding output terminals of the drive circuit, and wherein the driver IC is arranged face to face with respect to the head main body so that the input terminals and the output terminals are brought into contact with each other via the bumps.
As a result of such arrangement, it becomes easy to provide a structure which enables the driver IC to lie astride the actuator drive portion group, and, in addition, input terminal to output terminal connection can be established easily.
An arrangement may be made, wherein the input terminals of the plurality of actuators are arrayed along a first direction in parallel with the driver IC, and wherein a length of the driver IC in a second direction normal to the first direction is set longer than a length of the actuator drive portion group in the second direction.
As a result of such arrangement, there are provided several advantages. For example, it is possible to set the area of the driver IC greater than that of the head main body. In other words, the driver IC suffers from no constraints imposed by the area of the head main body. This accordingly increases the degree of freedom in design of the driver IC and the head main body.
An arrangement may be made, wherein each of the plurality of actuators is provided with a relay terminal for the relaying of a signal for driving the drive circuit of the driver IC, and wherein the ink-jet head further comprises auxiliary connecting members for establishing connection between each of the relay terminals and the drive circuit so that the signal can be fed to the drive circuit via the relay terminal.
As a result of such arrangement, the signal for driving the drive circuit is transmitted from a signal supply source such as the printer main body, thereafter being delivered to the drive circuit by way of the relay terminal or auxiliary connecting member provided in the actuator. Accordingly, there is no need to provide direct connection between the driver IC and the signal supply source, whereby the facilitation of manufacturing the ink-jet head can be improved and the cutdown of manufacturing costs is promoted. Furthermore, as the auxiliary connecting member, for example, a bonding wire or a bump may suitably be used.
It is preferred that at least the driver IC, the connecting members, and the input terminals of the plurality of actuators are sealed by an encapsulating material which is applied such that a specified clearance is formed between the encapsulating material and the actuator drive portion group.
Since at least the driver IC, the connecting members, and the actuator input terminals are all sealed, thereby preventing these components from capturing dust or the like, and their durability and reliability will be improved. In addition, it is possible to satisfactorily maintain electrical connection between terminals, thereby providing an improved reliability. Further, the actuator drive portion group is sealed, which therefore improves the reliability of the actuators. Since the encapsulating material is applied, with a given clearance formed between itself and the actuator drive portion group, the operation of the actuator drive portions will not be disturbed.
In order to accomplish the foregoing object, in the present invention, it is designed such that the driver IC having the drive circuit is disposed so as to overlap the actuator drive portions of the head main body, with a specified space formed therebetween.
The present invention embodies another ink-jet head. This ink-jet head comprises:
(a) a head main body in which a plurality of nozzles, a plurality of pressure chambers which correspond to the plurality of nozzles, respectively, and a plurality of actuators which correspond to the plurality of nozzles, respectively, are provided,
(b) a driver IC in which a drive circuit for outputting a drive signal to each of the plurality of actuators is provided,
(c) connecting members for establishing connection between the drive circuit and each of the plurality of actuators so that the drive signal is transmittable therebetween,
wherein each of the plurality of actuators includes an input terminal coupled to a corresponding one of the connecting members and a drive portion for producing drive force used to emit ink through a corresponding one of the plurality of nozzles upon receipt of the drive signal,
wherein a drive portion group composed of an array of the drive portions of the plurality of actuators is provided on one side of the head main body, and
wherein the driver IC is positioned on the outside of the drive portion group of the head main body, lying astride the drive portion group with a specified clearance formed between itself and the drive portion group.
Since the driver IC is provided on the outside of the actuator drive portion group of the head main body, lying astride the actuator drive portion group, there is no need to secure a space for the placement of the driver IC. This reduces the size of the head main body. Further, with the downsizing of the head main body, the cutdown of ink-jet head manufacturing costs can be possible. Owing to the arrangement that the driver IC is positioned at a given distance away from the actuator drive portion group, there is secured space for the operation of the actuator drive portion group. Accordingly, the operation will not be disturbed.
An arrangement may be made, wherein the driver IC is, at both ends thereof, fixedly supported on the head main body, and wherein the connecting members are bonding wires for establishing connection between the input terminals of the plurality of actuators and corresponding output terminals of the drive circuit.
The driver IC is, at the both ends thereof, supported on the head main body. As a result of such arrangement, the driver IC can easily be positioned on the outside of the actuator drive portion group, with a specified clearance formed between itself and the drive portion group. Further, input terminal to output terminal connection is established by means of a bonding wire, which facilitates connection between the input terminal and the output terminal.
An arrangement may be made, wherein the input terminals of the plurality of actuators are arrayed along a first direction in parallel with the driver IC, and wherein a length of the driver IC in a second direction normal to the first direction is set shorter than a length of the actuator drive portion group in the second direction.
As a result of such arrangement, there is created, along the second direction, a clearance between an output terminal of the drive circuit of the driver IC and an actuator input terminal of the head main body. This facilitates connecting together the output terminal of the drive circuit of the driver IC and the input terminal of the actuator of the head main body. In addition, wire bonding processes become easy to perform and the state of input terminal to output terminal connection is improved.
An arrangement may be made, wherein the connecting members are bumps for establishing connection between the input terminals of the plurality of actuators and corresponding output terminals of the drive circuit, and wherein the driver IC is arranged face to face with respect to the head main body so that the input terminals and the output terminals are brought into contact with each other via the bumps.
As a result of such arrangement, the driver IC can easily be located on the outside of the actuator drive portion group, with a given clearance formed between itself and the actuator drive portion group, and input terminal to output terminal connection can be established easily.
An arrangement may be made, wherein the input terminals of the plurality of actuators are arrayed along a first direction in parallel with the driver IC, and wherein a length of the driver IC in a second direction normal to the first direction is set longer than a length of the actuator drive portion group in the second direction.
Since the driver IC is disposed so as to overlap the head main body, with a given clearance formed between itself and the head main body, it is possible to determine the size of the driver IC without suffering from any constraints imposed by the area of the head main body. Accordingly, it is possible to increase the degree of freedom in design of the driver IC and the head main body.
It is preferred that at least the driver IC, the connecting members, and the input terminals of the plurality of actuators are sealed by an encapsulating material which is applied such that a specified clearance is formed between the encapsulating material and the actuator drive portion group.
Since the driver IC, the connecting members, and the actuator input terminals are all sealed, this prevents these components from capturing dust or the like, thereby improving their environmental resistance and reliability. Further, it becomes possible to satisfactorily maintain inter-terminal electrical connection, thereby providing improvement in reliability. Furthermore, the actuator drive portion group is sealed, thereby improving the reliability of the actuators. Since the encapsulating material is applied, with a given clearance formed between itself and the actuator drive portion group, the operation of the actuator drive portions will not be disturbed.
The present embodiment embodies a method of manufacturing an ink-jet head which includes (a) a head main body in which a plurality of nozzles, a plurality of pressure chambers which correspond to the plurality of nozzles, respectively, and a plurality of actuators which correspond to the plurality of nozzles, respectively, are provided, and (b) a driver IC in which a drive circuit for outputting a drive signal to each of the plurality of actuators is provided. More specifically, the ink-jet head manufacturing method includes:
(i) a step of temporarily affixing an adhesive to locations situated at both sides of a drive portion group composed of an array of a plurality of drive portions of the plurality of actuators in the head main body,
(ii) a step of placing the driver IC onto the adhesives so that the driver IC lies astride the drive portion group,
(iii) a step of wire bonding together, by means of bonding wires, output terminals of the drive circuit of the driver IC and corresponding input terminals of the plurality of actuators of the head main body.
As described above, an adhesive is temporarily affixed to locations situated at both sides of a drive portion group composed of an array of a plurality of drive portions of the actuators in the head main body. Then, the driver IC is placed onto the adhesive-carrying locations and hardening is carried out, whereby the driver IC will be, at the both ends thereof, firmly supported on the head main body in an easy manner. Further, the output and input terminals are wire bonded, thereby easily establishing inter-terminal connections.
An arrangement may be made, wherein the foregoing ink-jet head manufacturing method further includes, after the wire bonding step, a step of applying an encapsulating material in the form of a film which is greater in size than the driver IC onto the driver IC, the bonding wires, and the input terminals, and melting the encapsulating material in such a way as to prevent the encapsulating material from extending around to the sides of the drive portion group, whereby the driver IC, the bonding wires, and the input terminals will be sealed.
The encapsulating material in the form of a film is applied onto the driver IC, the bonding wires, and the input terminals of the head main body. Then, the applied encapsulating material is melted such that it will not extend around to the sides of the actuator drive portion group. Accordingly, the driver IC, the bonding wires, and the input terminals are sealed, without disturbing the operation of each of the drive portions of the actuators.
The present invention embodies another method of manufacturing an ink-jet head which includes (a) a head main body in which a plurality of nozzles, a plurality of pressure chambers which correspond to the plurality of nozzles, respectively, and a plurality of actuators which correspond to the plurality of nozzles, respectively, are provided, and (b) a driver IC in which a drive circuit for outputting a drive signal to each of the plurality of actuators is provided. More specifically, the ink-jet head manufacturing method includes:
(i) a step of forming bumps on at least either output terminals of the drive circuit of the driver IC or input terminals of the plurality of actuators of the head main body,
(ii) a step of placing the head main body and the driver IC face to face with respect to each other so that the input terminals and the output terminals are brought into contact with each other via the bumps, and joining together the head main body and the driver IC so that drive portions of the plurality of actuators of the head main body are not brought into contact with the driver IC.
Owing to such arrangement, the input and output terminals are brought into contact with each other through the bumps. On the other hand, the driver IC and the head main body are jointed together face to face in order not to bring the actuator drive portions into contact with the driver IC. Accordingly, the driver IC is disposed easily in an overlapping manner with the head main body. Output terminal to input terminal connection can be established easily, and, at the same time, operation space for each actuator drive portion is secured.
An arrangement may be made, wherein the aforesaid ink-jet head manufacturing method further includes, after the step of joining together the head main body and the driver IC, a step of applying an encapsulating material in the form of a film which is greater in size than the driver IC, onto the driver IC and the input terminals of the plurality of actuators, and melting the encapsulating material so that the encapsulating material will not extend around to the sides of the actuator drive portions, for sealing the driver IC, the bumps, and the input terminals.
The encapsulating material in the form of a film is applied onto the driver IC and the head main body. Then, the applied encapsulating material is melted such that it will not extend around to the sides of the actuator drive portions. Accordingly, the driver IC, the bumps, and the input terminals are sealed, without disturbing the operation of each of the actuator drive portions.